Protective Cap for Arthroscopic Instruments

ABSTRACT

A protective cap for use on arthroscopic instruments and sheaths disposed over arthroscopic instruments. The cap protects the distal end of the instrument from accidental damage caused by other instruments used during a surgical procedure. The portion of the cap that covers a view port on an arthroscope is transparent in order to allow a user to see through the instrument and through the cap.

This application is a continuation of U.S. patent application Ser. No.12/491,566 filed Jun. 25, 2009, now U.S. Pat. No. 8,216,131, which is acontinuation of 11/142,990, filed Jun. 1, 2005, now U.S. Pat. No.7,553,278.

FIELD OF THE INVENTIONS

The inventions described below relate the field of arthroscopic surgicalinstruments.

BACKGROUND OF THE INVENTIONS

Arthroscopic surgery involves using optical instruments, such as anarthroscope, to visualize an operating field inside or near a joint of apatient. The same instrument or other instruments may be used to performa surgical procedure in the operating field. Common instruments used inaddition to the arthroscope include a trimming instrument for cuttingtissue and an irrigation instrument for irrigating the surgical field.Each of the instruments requires its own incision to be introduced intothe surgical field; thus, many surgeons prefer to use only a trimminginstrument and an arthroscope during arthroscopic surgical procedures.

Arthroscopes are fragile in relation to the forces applied duringarthroscopic surgery, so a rigid cannula is placed over the arthroscopeto reinforce it. The distal end of the rigid cannula is pointed, usuallysharp, and so the rigid cannula can scratch or gouge soft tissue withinthe operating field. The rigid cannula can also become stuck betweenbones or cartilage during a procedure. A rigid cannula can also damagemetal prosthetics used to replace joints, resulting in a shortening ofthe useful life of the prosthetic and forcing the patient to undergoadditional, painful surgeries to correct the problem.

An additional problem associated with arthroscopic surgery ismaintaining a clear surgical field during surgery. Blood and debris cancloud the field, impairing a surgeon's ability to visualize tissue. Onemethod of solving this problem is to use the irrigation instrument toclear the surgical field with saline; however, many surgeons stronglyprefer to avoid the additional trauma caused by inserting a thirdinstrument. These surgeons will perform arthroscopic surgeries despiteproblems with visualizing the surgical field.

A further problem associated with arthroscopic surgery is accidentaldamage to the arthroscope. The arthroscope is often damaged if theworking end of a trimming instrument accidentally strikes the sensitiveoptical components on the distal portion of the arthroscope. Thearthroscope may also be damaged if the arthroscope becomes stuck betweenbones, cartilage or other tissue and excessive force must be used tofree the arthroscope. Arthroscopes are expensive, costing thousands ofdollars, so accidental damage to arthroscopes is a significant costproblem.

A damaged arthroscope could cause delays during surgery and brokenpieces of the arthroscope could be deposited in the surgical field. Bothsituations are harmful to the patient. Thus, devices and methods areneeded to prevent accidental damage to arthroscopes during surgery.

SUMMARY

The methods and devices shown below provide for a protective cap that isplaced over the distal portion of an arthroscope. The cap is made of atransparent, yet durable material that prevents accidental damage to thearthroscope caused by trimming instruments or impacts with hard tissuewithin the surgical field. Holes may be placed in the cap to provide forthe inflow and outflow of fluids from the cap. One or more lenses orfilters may be provided within the cap to adjust the field of view asseen through the arthroscope.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a method of performing arthroscopic surgery on a patient.

FIG. 2 shows a protective cap disposed over the distal portion of anarthroscopic instrument.

FIG. 3 shows a cross section of a protective cap disposed over thedistal portion of an arthroscopic instrument.

FIG. 4 shows a cross section of a multi-lumen protective cap.

FIG. 5 shows a protective cap having a concave lens disposed at thedistal end of the cap.

FIG. 6 shows a protective cap having a convex lens disposed at thedistal end of the cap.

FIG. 7 shows cap with a reticule for use with an arthroscopicinstrument.

FIG. 8 shows a reticule for use with an arthroscopic instrument.

FIG. 9 illustrate an atraumatic sheath for use over an endoscopeprovided with a mirror having a hinge.

FIG. 10 illustrates an atraumatic sheath devices that allows viewingaround an obstruction.

FIG. 11 shows a protective cap over an arthroscopic sheath.

FIG. 12 shows a cross-section of protective cap over an arthroscopicsheath.

DETAILED DESCRIPTION OF THE INVENTIONS

FIG. 1 shows a method of performing arthroscopic surgery on a patientusing an arthroscopic instrument 2 sheathed in an atraumatic introducersheath 3. (The various parts of the arthroscope are shown in phantom toindicate their positions inside the sheath.) Various anatomicallandmarks in a patient's knee 4 are shown for reference, including thefemur 5, patella 6, posterior cruciate ligament 7, anterior cruciateligament 8, meniscus 9, tibia 10 and fibula 11. During surgery, thesurgeon introduces the arthroscope 2 into the knee via a first incision12 in order to visualize the surgical field. A trimming instrument 13 isintroduced through a second incision 14 to remove or trim tissue thatthe surgeon determines should be removed or trimmed. Optionally, anirrigating instrument 15 may be introduced through a third incision 16in order to irrigate the surgical field and thereby maintain a clearview. As illustrated below, a combined arthroscope and inflow/outflowatraumatic sheath may replace the irrigating instrument.

The arthroscope 2 is an optical instrument 17 surrounded by a rigidcannula 18 having a distal edge that typically is cut at an angle. Toprotect the patient from unintended injury or trauma during theprocedure, the arthroscope has been inserted into a resilient outerintroducer sheath or atraumatic sheath 3 that extends over the rigidcannula. Preferably, the distal tip 19 of the atraumatic sheath extendsdistally just past the distal end of the arthroscope and rigid cannulato further protect the patient.

FIGS. 2 and 3 show an atraumatic protective cap 30 having a cap body 28and a lens 29 and disposed over the distal portion 31 of an arthroscopicinstrument. The cap body 28 is sized and dimensioned and of such aprofile as to allow passage into restricted joint anatomy. Preferably,the cap is disposed on the end of the sheath 3 and slides over thedistal end of the arthroscope as the sheath is pulled over thearthroscope as shown in FIG. 2. (The sheath is also shown in ourco-pending application 10/769,629, filed Jan. 29, 2004, which is herebyincorporated by reference in its entirety.) The sheath can be a tube ofpolymeric material sized and dimensioned to slip fit over the outersurface of a cannula or endoscope. The sheath may further be providedwith longitudinal ribs characterizing fluid flow lumens between theouter surface of the cannula and the inner surface of the sheath. Thecap, however, may also be provided as a separate device from the sheathas illustrated in FIG. 3. The cap is preferably provided with a rounded,or bulbous, shape that reduces the chances of injuring tissue during thesurgical procedure. The cap is optically transparent to wavelengths oflight used during surgery, though only that portion of the cap coveringthe view port of the arthroscope need be transparent. (The view port isthat portion of the arthroscope through which the surgeon visualizes thesurgical field.) The material of the cap is sufficiently durable thatthe cap will prevent accidental damage to the arthroscope caused byunintended contact with the working end of a trimming instrument, byunintended contact with burrs or other hard tissue within the surgicalfield or because of excessive force applied to the arthroscope.Preferably, the body of the cap may be manufactured from thermoplasticelastomers. However, other materials used to manufacture the body of thecap may include styrenic block copolymers (SBCs), thermoplastic olefins(TPOs), thermoplastic vulcanisates (TPVs), thermoplastic polyurethaneelastomers (TPUs), copolyesters (COPEs) and copolyamides (COPAs).Thermosets such as silicone, urethane or latex may also be used tomanufacture the cap body. Sterilizable elastomers are typically used tomake the body of the cap while optically clear polycarbonate materialscomprise the viewing lens 29 in the cap 30. Other materials suitable forthe viewing lens include molded acrylic, styrene, polyolefin or silicon.Alternatively, the body of the cap and lens can also be manufacturedfrom the same optically clear material reducing manufacturing andassembly costs. Such suitable material includes optically clear siliconeavailable from Wacker Silicones™ and having a hardness ranging fromapproximately 30 Shore A to approximately 40 Shore D.

One or more holes 32 may be placed in the cap to provide for suction,irrigation or the injection of therapeutic agents. Similar holes 33 mayalso be placed in the sheath. The holes are in fluid communication withone or more of the lumens disposed in the sheath or arthroscope ordisposed between the sheath and arthroscope. A fluid source 34 in fluidcommunication with one or more lumens is provided to irrigate thesurgical field or to inject therapeutic agents into the surgical field.A vacuum source 35 in fluid communication with one or more of the lumensprovides suction. A manifold 36 disposed on the sheath or arthroscopedistributes the flow of fluids within the sheath or arthroscope.

In use, the sheath and protective cap are pulled over the arthroscope.The surgeon then inserts the arthroscope into the surgical field andsubsequently performs a surgical procedure on the patient. If, duringthe procedure, the working end of a trimming instrument accidentallystrikes the cap, the cap will prevent damage to the arthroscope.Likewise, the cap will prevent damage to the arthroscope if thearthroscope strikes a burr or other hard piece of tissue. Preferably,the cap is releasably attached to the sheath so that the cap may beeasily replaced if damaged by these events.

FIG. 4 shows a cross section of a multi-lumen protective cap 30 and anarthroscope 2 disposed within the cap. One or more holes 37 extend fromthe outer diameter of the cap to the outer lumen 38. In addition, one ormore additional holes 39 extend from the outer diameter of the cap,through the outer lumen and to the inner lumen 40 of the cap. The holes39 communicating with the inner lumen do not communicate with the outerlumen, thereby isolating the inner and outer lumens. Thus, suction maybe provided through one lumen and simultaneous irrigation providedthrough the other lumen. Alternatively, the cap may be provided as partof a system providing fluid inflow and outflow to a surgical site wherefluid inflow and outflow is accomplished by devices other than anarthroscope or arthroscope sheath.

The cap 30 or cap body 28 shown in FIGS. 2 through 4 may be integrallyformed with a sheath 3, attached to a sheath 3, or fit over a sheath 3.The cap may also be provided without the sheath. The cap may be placeddirectly over the distal portion of the arthroscope without anatraumatic sheath. The cap can be held to the arthroscope by frictionfit between the scope and the cap, by a shrink tube, by an adhesive, bydetents or by any other suitable mechanism. Preferably, the cap isremovably attached so that the cap may be easily replaced. As with thecap disposed on the sheath, holes 32 may be provided to provide for theinflow and outflow of fluids.

FIG. 5 shows a protective cap 30 having a concave lens 53 disposed atthe distal end of the cap. The lens is provided just inside and proximalthe distal end of the cap. The concave lens provides for a wide-angleview of the surgical field.

FIG. 6 shows a protective cap 30 having a convex lens 54 disposed at thedistal end of the cap. The lens is provided just inside and proximal thedistal end of the cap. The convex lens provides for a magnified view ofan object within the surgical field.

FIG. 7 and FIG. 8 show a reticule 55 for use with an arthroscopicinstrument. The reticule may be etched into a lens 29 disposed withinthe cap or may be otherwise suitably placed on the cap or even onarthroscope itself. The reticule is marked with a scale 56 with whichthe surgeon can measure the size of objects seen through thearthroscope. The surgeon may also use the reticule to align thearthroscope within the surgical field.

In addition to the lenses and reticule shown in FIGS. 5 through 8,filters may be provided within the cap to reduce light reflected intothe arthroscope or to block certain wavelengths of light. The filteredlens may comprise a polarizing filter, a bandpass filter, a colorfilter, or an interference filter. These filters can be used inconjunction with specialized light sources (e.g. Ultraviolet orInfrared) and video processing for therapeutic and diagnostic purposes.Thus, the cap may be part of a complete system to diagnose pathologyusing different wavelengths of light and/or colors of light andfiltering the light. Further, the cap may also be provided as part ofsystem that delivers photonic energy to a surgical site to control andvisualize photodynamic therapy.

Other lenses, such as spherical lenses, may also be provided within thecap to change the field of view. Multiple lenses may also be providedwithin the cap to adjust the field of view. As illustrated in FIGS. 9and 10, the sheath, the cap or the sheath with the cap combination maybe configured to allow viewing around an object or obstruction. This maybe accomplished through the use of a right angle prism, pentaprism, roofprism, retro-reflector or mirror disposed within the cap. The mirror maybe flat, concave or convex to produce a normal, reduced, or magnifiedimage. As illustrated in FIG. 9, an atraumatic sheath 3 for use over anendoscope is provided with a mirror 67 having a hinge 68. A pull-wire 69is coupled to the mirror 67 and is disposed within the sheath 3. Thepull-wire 69 is further coupled to an articulating knob 70. When theknob is manipulated, the pull-wire moves the mirror and changes theviewing angle 71.

FIG. 10 illustrates an atraumatic sheath 3 device that allows viewingaround an object or obstruction through the use of a deflectablematerial or flexible mount 72 having a mirror 67. The mount may bemanufactured from formable materials such as aluminum or steel havingspring characteristics. A pull-wire 69 or other manipulation device mayalso be coupled to the mount to change viewing angle 71 when the wire ismanipulated manually using an articulating knob 70. The mount may alsobe manufactured from shape memory materials such as Nitinol® that may bemanipulated using electrical current to change the angle of the mirror.The cap and the sheath with the cap may also be modified for use withother types of endoscopes or for use with other delicate instrumentsthat are subject to damage during a surgical procedure.

FIGS. 11 and 12 illustrate a protective cap 30 over an arthroscopicsheath 3. The sheath 3 comprises an inner lumen 61 in fluidcommunication with a vacuum source and a hole dispose 33 in the sheathin fluid communication with the vacuum source and a surgical site withina patient 1. A backstop or flange 63 is disposed within an innerdiameter of a bore within the cap. The bore is sized and dimensioned tofriction fit over the sheath 3.

The flange 63 prevents the sheath 3 from being further pushed into thecap and extends inwardly to come in contact with an outer diameter ofthe rigid cannula 18 disposed within the sheath 3. This contact forms aseal between the flange 63 and the outer diameter of the rigid cannula18. The rigid cannula 18 is provided with a lumen in fluid communicationwith a fluid source the cap. Holes 32 disposed in the cap are in fluidcommunication with the surgical site and the lumen within the rigidcannula 18 as well as the fluid source allowing fluid to flow from thefluid source to the surgical site. The cap further comprises a concavelens 53 coupled to the distal portion 64 of the cap 3.

Thus, while the preferred embodiments of the devices and methods havebeen described in reference to the athroscopic surgical environment inwhich they were developed, they are merely illustrative of theprinciples of the inventions. Other embodiments and configurations foruse with other types of endoscopes may be devised for use in othersurgical and non-surgical environments without departing from the spiritof the inventions and the scope of the appended claims.

1. A cap in combination with an arthroscope disposed within a rigidcannula, said, said cap comprising: a body bulbous in shape andcharacterized by a distal end and proximal end; a bore having an innerdiameter and disposed within the body, said inner diameter of said boresized and dimensioned to friction fit over an outer diameter of a rigidcannula; a lens coupled to the distal end of the body and operablycovering an objective lens of an arthroscope disposed within the rigidcannula.
 2. The cap of claim 1 wherein the lens is concave.
 3. The capof claim 1 wherein the lens is convex.
 4. The cap of claim 1 furthercomprising a filter.
 5. The cap of claim 1 further comprising a holedisposed in an outer surface of the cap, said hole being in fluidcommunication with a lumen disposed in the arthroscope, and wherein afluid source is in fluid communication with the lumen.
 6. The cap ofclaim 1 wherein a hole is disposed in an outer surface of the cap, saidhole being in fluid communication with a lumen disposed in thearthroscope, and wherein a vacuum source is in fluid communication withthe lumen.
 7. An atraumatic sheath in combination with an arthroscopicinstrument disposed within a rigid cannula, said sheath comprising: atube characterized by a distal section and a proximal section whereinthe inner diameter of said tube is sized and dimensioned to fit over anouter surface of the rigid cannula when the rigid cannula is disposedwithin the tube; and a cap coupled to the distal end of the tube;wherein said cap comprises a body bulbous in shape characterized by adistal end and proximal end, a bore having an inner diameter anddisposed within the body, said inner diameter of said bore sized anddimensioned to friction fit over an outer diameter of the rigid cannula,and a lens coupled to the distal end of the body and operably coveringan objective lens of the arthroscopic instrument disposed within therigid cannula; said tube further comprising a mirror operably coupled tothe distal end of the body and operably covering the objective lens ofthe arthroscopic instrument.
 8. The atraumatic sheath of claim 7 whereinthe mirror is operably connected to a pull wire and an articulatingknob.